Dissertations / Theses on the topic 'Composite materials Al'
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Freitas, Ricardo Luiz Barros de [UNESP]. "Fabricação, caracterização e aplicações do compósito PZT/PVDF." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/100281.
Full textConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Um material compósito é constituído pela combinação de dois ou mais materiais, onde se procura sintetizar um novo material multifásico, e que abrigue as melhores características individuais de cada um de seus constituintes. Compósitos de polímeros (matriz) e ferroelétricos (inclusões) podem manifestar piezoeletricidade, ou seja, a produção de uma resposta elétrica devido a uma excitação mecânica, e vice-versa. Nesta tese o material polimérico usado para preparar os filmes ou lâminas de nanocompósitos é o PVDF, e, o material cerâmico é formado por nanopartículas de PZT. Ambos os materiais são dielétricos, porém, com características muito distintas (por exemplo, o PVDF tem aproximadamente 1/4 da densidade e 1/250 da constante dielétrica do PZT). O PZT é muito utilizado em transdutores, principalmente devido aos seus elevados coeficientes piezoelétricos, contudo, é quebradiço e sofre desgaste quando empregado na forma de filmes ou lâminas. Por outro lado, o PVDF é um polímero piezoelétrico que apresenta grande flexibilidade e excelentes resistências mecânica e química, porém, seus coeficientes piezoelétricos são apenas moderados. A fim de se aumentar a flexibilidade do PZT, mistura-se o pó cerâmico, na forma de nanopartículas, com o PVDF, também pulverizado. Na tese, evidencia-se que o compósito constituído por esta combinação cerâmica-polímero proporciona uma nova classe de materiais funcionais com grande potencial de aplicação, por terem combinadas a resistência e rigidez das cerâmicas, e, a elasticidade, flexibilidade, baixa densidade e elevada resistência a ruptura mecânica dos polímeros. O novo material tem grande resistência a choques mecânicos, flexibilidade, maleabilidade, e, principalmente, coeficientes piezoelétricos relativamente elevados. Amostras do compósito...
A composite material is constituted by the combination of two or more materials, which synthesizes a new multiphase material, and has the best individual characteristics of each of its constituents. Polymer composites (matrix) and ferroelectric (inclusions) can express piezoelectricity, i.e. the production of an electrical response due to a mechanical excitation, and vice versa. In this thesis the polymeric material used to prepare the films or slides of nanocomposites is the PVDF, and, ceramic material is formed by PZT nanoparticles. Both materials are dielectrics, however, with very different characteristics (for example, the PVDF is approximately 1/4 density and 1/250 relative permittivity from PZT). The PZT is widely used in transducers, mainly due to their high piezoelectric coefficients, however, is brittle and suffers wear and tear when employed in the form of films or slides. On the other hand, the PVDF is a piezoelectric polymer that offers great flexibility and excellent mechanical and chemical resistances, however, its piezoelectric coefficients are only moderate. In order to increase the flexibility of PZT, ceramic powder is mix, in the form of nanoparticles, with PVDF, also sprayed. In theory, it becomes evident that composite consisting of this ceramic- polymer combination delivers a new class of functional materials with great potential for application, because they combine the strength and rigidity of ceramics, and elasticity, flexibility, low density and high resistance to mechanical disruption of polymers. The new material has great resistance to mechanical shock, flexibility, suppleness, and, primarily, relatively high piezoelectric coefficients. PZT/PVDF composite samples were fabricated and characterized aiming to applications such as: piezoelectric actuators, acoustic emission detectors, and energy... (Complete abstract click electronic access below)
Palmer, Nathan Reed. "Smart Composites evaluation of embedded sensors in composite materials /." Thesis, Montana State University, 2009. http://etd.lib.montana.edu/etd/2009/palmer/PalmerN0809.pdf.
Full textKarlsson, Johan. "Composite material in car hood : Investigation of possible sandwich materials." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-45633.
Full textPodnos, Eugene Grigorievich. "Application of fictitious domain method to analysis of composite materials /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
Full textYan, Chang (Karen). "On homogenization and de-homogenization of composite materials /." Philadelphia, Pa. : Drexel University, 2003. http://dspace.library.drexel.edu/handle/1860/246.
Full textSymington, Mark C. "Cellulose based composite materials." Thesis, University of Strathclyde, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501684.
Full textDyer, K. P. "Fatigue of composite materials." Thesis, Swansea University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636755.
Full textYang, Heechun. "Modeling the processing science of thermoplastic composite tow prepreg materials." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/17217.
Full textGambone, Livio R. "The effect of R-ratio on the mode II fatigue delamination growth of unidirectional carbon/epoxy composites." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/29968.
Full textApplied Science, Faculty of
Materials Engineering, Department of
Graduate
Counts, William Arthur. "Mechanical behavior of bolted composite joints at elevated temperature." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/17315.
Full textWood, Geoffrey Michael. "Treatment of polyethylene fibre for improved fibre to resin adhesion in composite applications." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28528.
Full textApplied Science, Faculty of
Materials Engineering, Department of
Graduate
Teh, Kuen Tat. "Impact damage resistance and tolerance of advanced composite material systems." Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06062008-170512/.
Full textZhang, Fangzhou. "Multiscale modeling of laminated composites under extreme environmental conditions." Thesis, Cachan, Ecole normale supérieure, 2014. http://www.theses.fr/2014DENS0027/document.
Full textAt high temperature, the oxygen reacts with the organic matrix of composite material, which changes the material properties and reduces the resistance to global failure. But understanding on the degradation of the oxidized composite laminate, particularly its damage behavior, is now limited and phenomenological. Work in this thesis has been made to give our contribution to the methodological aspects of this topic. Tests are performed to characterize experimentally the behaviors of the oxidized specimens: in particular, a new test test oxy-delamination ', was developed to identify the tenacity of composite material aged. A strategy has been proposed to study the problem from the properties the oxidized matrix at the fiber/matrix scale up to the reproduction and predicting the behavior of transverse cracking of the sample at the scale of a ply via a homogenization process
Biggerstaff, Janet M. "Vibrational Damping of Composite Materials." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3204578.
Full textTitle from first page of PDF file (viewed April 3, 2006). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 218-224).
Liu, Liu. "Durability of Polymer Composite Materials." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14002.
Full textMatemilola, Saka Adelola. "Impact damage to composite materials." Thesis, University of Cambridge, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319939.
Full textMurphy, Craig E. "Pyroelectric thin film composite materials." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260162.
Full textDelfa, G. L. a. "Aerospace composite materials in fire." Thesis, University of Newcastle Upon Tyne, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519566.
Full textAlur, Kashyap. "Nonlinear mechanics of composite materials." Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53600.
Full textZhu, Fuyou. "Advanced materials for composite armour." Thesis, Queen Mary, University of London, 2009. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1775.
Full textBuck, Lyndon. "Furniture design with composite materials." Thesis, Bucks New University, 1997. http://bucks.collections.crest.ac.uk/9977/.
Full textBeglinger, Jarrod (Jarrod Thomas) 1976. "Forming of advanced composite materials." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/31077.
Full textIncludes bibliographical references (p. 45).
Two significant aspects of advanced composite material forming are examined. First, the fiber deformation of aligned fiber composites formed to double curvature parts is analyzed. Aligned fiber composite lay-ups were formed over hemispherical tools and the fiber deformation was mapped. The data were intended to support the model which predicts trellising of composite fibers in double curvature. The data are, in general, too ambiguous to clearly support this model. Second, springback of woven fiber material-single curvature parts is investigated. A 90° bend was formed for varying laminate lay-ups at varying temperatures via a double diaphragm process. Principal objectives were to qualify the effects of varying lay-ups and temperatures on the net amount of springback observed. The data show that 0/90 woven lay-ups experience more springback than either +45 degree or quasi-isotropic woven lay-ups, and that heating the laminates marginally decreases the springback experienced.
by Jarrod Beglinger.
S.B.
Venkatasubramanian, Rajiv. "Composite Nanoparticle Materials for Electromagnetics." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1352993374.
Full textBaker, Christopher R. "Assessing Damage in Composite Materials." University of Akron / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=akron1390315001.
Full textWhiteside, M. B. "Stochastic analysis of composite materials." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/9986.
Full textVukicevic, Uros. "TiO2 nanorod polymer composite materials." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/7669.
Full textPospíšil, Tomáš. "STOCHASTIC MODELING OF COMPOSITE MATERIALS." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-233889.
Full textSomanath, Nagendra. "A finite element cure model and cure cycle optimization for composite structures." Thesis, This resource online, 1987. http://scholar.lib.vt.edu/theses/available/etd-04272010-020304/.
Full textCall, Russell Kent. "Parameter establishment and verification of a fabrication stress model and a thermo-kinetic cure model for filament wound structures." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-08142009-040256/.
Full textWright, Richard J. "Bolt bearing creep behavior of highly loaded polymer matrix composites at elevated temperatures." Thesis, Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/17362.
Full textBulsara, Vatsal N. "Effects of fiber spatial distribution and interphase on transverse damage in fiber-reinforced ceramic matrix composites." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/21429.
Full textGopalan, Sriram. "Quasi-static and dynamic mechanical characterization of reinforced polyurethane foam /." free to MU campus, to others for purchase, 2003. http://wwwlib.umi.com/cr/mo/fullcit?p1418024.
Full textChang, Sheau-Miin. "Critical evaluation of strong organic fibers vis-a-vis mechanical performance in flexible structures." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/8479.
Full textKokan, David R. "Development and use of an improved filament-winding process model." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/12261.
Full textWard, William F. "A theoretical investigation into the inelastic behavior of metal-matrix composites." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/17244.
Full textVeazie, David R. "Modeling of fiber reinforced composites incorporating distinct interface properties." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/17385.
Full textKothidar, Arjun. "Use of finite element method to evaluate the strength response of notched composite laminates under tension." Pullman, Wash. : Washington State University, 2008. http://www.dissertations.wsu.edu/Thesis/Fall2008/A_Kothidar_120508.pdf.
Full textTitle from PDF title page (viewed on July 6, 2009). "Department of Mechanical and Materials Engineering." Includes bibliographical references (p. 115-118).
Enemuoh, Emmanuel Ugochukwu. "Smart drilling of advanced fiber reinforced composite materials /." free to MU campus, to others for purchase, 2000. http://wwwlib.umi.com/cr/mo/fullcit?p9998482.
Full textJames, Aaron. "Development of composites materials from waste paper and plastic." Australian Digital Thesis Program, 2006. http://adt.lib.swin.edu.au/public/adt-VSWT20070130.165426/index.html.
Full textA thesis submitted for the degree of Doctor of Philosophy, Industrial Research Institute Swinburne, Swinburne University of Technology - 2006. Typescript. "August 2006". Includes bibliographical references (p. 361-389).
Klug, Jeremy Hager. "High-performance adhesive systems for polymer composite bonding applications /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/9883.
Full textLee, Jaehong. "Vibration, buckling and postbuckling of laminated composites with delaminations." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-06062008-170322/.
Full textLorandi, Natália Pagnoncelli. "Estudo das propriedades dinâmico-mecânicas e fluência de compósitos epóxi/tecido não-dobrável de carbono produzidos por VARTM e RFI." reponame:Repositório Institucional da UCS, 2016. https://repositorio.ucs.br/handle/11338/1844.
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The excellent cost-weigh-performance relationship of polymeric composites compared to traditional materials became a reason to development of advanced materials for structural application such as carbon/epoxy composites, and with that, new processing methods, different resins (matrix) and fabrics (reinforcement) producing. Polymers and their composites present viscoelastic behavior, and so issues such as dimensional stability and long-term resistance must be taken into account when used by aeronautic industry. Dynamic-mechanical analysis (DMA) allows the evaluation of viscoelastic properties, and with creep tests, it is possible to study materials strain as function of time, under constant stress and temperature. In this study, epoxy/carbon NCF composites were manufactured by two techniques: vacuum assisted resin transfer molding (VARTM) and resin film infusion (RFI), and a comparative analysis between both composites was made. Storage modulus, E’, for RFI composite was approximately 10 GPa higher along the glassy region and Tonset approximately 60°C higher than VARTM composite. RFI composite also presented a wider glass transition region (form tan δ curve). These results were associated to the molecular relaxation and higher chain cooperative motion, and to the higher stiffness of RFI composite. Creep strain tests were performed in three different stress levels and temperatures, and VARTM composite presented larger creep strain with time, indicating a weaker interface fiber/matrix and a lower stiffness composite, and corroborating with short-beam shear resistance. Findley and Burger’s model were applied and both agreed well with experimental creep curves. Parameters of each model were associated to composites viscoelastic behavior and they were related to the other results.
Smith, Jay David. "Internal damage characterization for composite materials under biaxial loading configuration." Thesis, Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/smith/SmithJ0507.pdf.
Full textWu, Xiang. "Thermoforming continuous fiber reinforced thermoplastic composites." Diss., Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/9383.
Full textHsu, Sheng-yuan. "On the prediction of compressive strength and propagation stress of aligned fiber-matrix composites /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.
Full textZaghi, Stefano. "Multiscale multiphysics simulation in composite materials." Doctoral thesis, Universitat Politècnica de Catalunya, 2019. http://hdl.handle.net/10803/665129.
Full textEn las últimas décadas, el avance en términos de poder computacional ofrece la capacidad de analizar más detalladamente el comportamiento de los materiales. Por un lado, profundizar los materiales para estudiar una dimensión cada vez más pequeña y capturar micro o nanocambios. Por otro lado, la capacidad de memoria computacional permite realizar análisis de elementos finitos con miles de millones de nodos, lo que permite obtener resultados lo más exacto posible. El objetivo de este trabajo es la modelización numérica del comportamiento microescala de materiales no homogéneos, con especial atención a los materiales compuestos, en condiciones de carga termo-mecánica, y la aplicación de herramientas de optimización de las leyes constitutivas, así como en a nivel macro y micro estructural. La tesis se propone como un compendio de artículos publicados en revistas internacionales. En la primera publicación, se presenta un micro-modelo basado en el daño mecánico, capaz de representar los comportamientos mecánicos de las estructura de mampostería. El micro-modelo propuesto se basa en un modelo de daño continuo por tensión-compresión. La adopción de criterios de daño apropiados permite al analista controlar la dilatancia del material, aunque este aspecto no está generalmente asociado a los modelos de daño continuo como lo es para los modelos de plasticidad. El estudio propone una solución simple a este problema, que consiste en la definición apropiada de las superficies de daño bajo estados de tensión de cortante junto con la formulación de leyes de evolución apropiadas para las variables de daño. El modelo mantiene el formato simple y eficiente de los modelos de daños clásicos, donde la evaluación explícita de las variables internas evita los procedimientos iterativos anidados, aumentando así el rendimiento computacional. Otro objetivo de esta investigación es realizar una comparación crítica del micro-modelo continuo propuesto con otras dos estrategias bien conocidas de micro-modelado discreto. Posteriormente, se presenta una metodología termomecánica multiescala completa, que cubre las escalas nano, micro y macroscópica. En dicha metodología, derivada directamente del Método Multiescala de Primer Orden, las propiedades fundamentales del material se determinan mediante simulaciones de dinámica molecular que se implementan en consecuencia a nivel microestructural por medio de análisis de elementos finitos. Por otro lado, el problema de macroescala se resuelve considerando el efecto de la microestructura mediante homogeneización termo-mecánica en un elemento de volumen representativo (RVE). Finalmente, se proponen dos procedimientos multiescala computacionalmente eficientes capaces de predecir la respuesta mecánica no lineal de materiales compuestos. Esto se logrará utilizando una base de datos (DB) calculada a priori. A través de las definiciones de un parámetro de daño equivalente (d_eq), funciónes de la tensión global de la microescala, se actuarán una serie de pruebas virtuales de la microescala con deformación controlada para almacenar en el DB el estrés y la tensión homogeneizadas alcanzado en ciertos niveles de d_eq. Posteriormente, la solución de la estructura de macroescala mediante el método multiescala de primer orden se reemplazará por la interpolación de los datos almacenados en el DB. El primer método propuesto, llamado Discrete Multiscale Threshold Surface (DMTS), proporcionará la generación de la RVE en la parte no lineal de la estructura, mientras que el segundo, llamado Discrete Multiscale Constitutive Model (DMCM), es completamente independiente del micromodelo porque solo se utiliza la información de estrés almacenada en el DB. En el articulo se ha prestado especial atención a la creación y validación de la base de datos y al estudio de una estructura compuesta completa comparando la aceleración en terminos de tiempo computationál obtenido
Mutnuri, Bhyrav. "Thermal conductivity characterization of composite materials." Morgantown, W. Va. : [West Virginia University Libraries], 2006. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=4468.
Full textTitle from document title page. Document formatted into pages; contains vii, 62 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 61-62).
Mårtensson, Eva. "Modelling electrical properties of composite materials." Doctoral thesis, KTH, Electrical Systems, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3594.
Full textComposite field grading materials are used to avoid stressconcentrations in high voltage applications such as cableaccessories and generator or motor end windings. The compositematerials consist of an insulating matrix filled with suitableconducting or semi-conducting particles. Silicon carbide (SiC)powder is one such filler that is being employed. The compositematerials display complex electrical characteristics that aredependent on filler properties, particle concentration,frequency and electric field. Optimization of the stressgrading properties would be facilitated if the characteristicof a specified material mixture could be calculatedapproximately.
In this thesis a microscopic model for the local behavior atthe SiC grain contacts as well as a macroscopic model for theglobal performance of the composite material are presented. Thedc and ac characteristics of different SiC powders and variouscomposite materials have been studied by experiments andsimulations. The electrical properties of ethylenepropylene-diene monomer (EPDM) rubber filled with the SiC grains havebeen characterized by several time and frequency domainmeasurement techniques.
It is shown that the SiC grain contacts can be modeled bySchottky-like barriers. The SiC powders are heavily doped andthe dominating conduction mechanismin the major part of thefield range is tunneling by field emission, amplified bypre-avalanche multiplication. The frequency dependentproperties are governed both by the interfacial barrier regionsand by the surrounding dielectric.
A three-dimensional electrical network model for describingthe frequency dependent electrical properties of the compositematerials has been developed. Accounting for different types ofcontacts between the filler grains is fundamental for theresulting characteristics. The distribution of the conductingparticles in the matrix also affects the electrical propertiesand a well dispersed, and not only random, arrangement is morerealistic. Non-linearity is incorporated in an amended version,which treats the timedependent case.
The model has been implemented in a MATLAB® program andthe calculations have been compared to measurements on EPDMrubber filled with SiC grains. It is demonstrated that thenetwork simulations reproduce the general characteristics ofrelevant concentration, frequency and field dependentexperimental results.
Keywords:field grading; composite materials; SiC;rubber; electrical properties; nonlinear; time-dependent;model; network; conduction mechanisms; Schottky-barrier;
Bonnaud, Etienne. "On mechanical modeling of composite materials." Doctoral thesis, KTH, Hållfasthetslära (Avd.), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-24644.
Full textRussell, Benjamin Peter. "The micromechanics of composite lattice materials." Thesis, University of Cambridge, 2010. https://www.repository.cam.ac.uk/handle/1810/252176.
Full text